//<p>将一个给定字符串 <code>s</code> 根据给定的行数 <code>numRows</code> ，以从上往下、从左到右进行 Z 字形排列。</p>
//
//<p>比如输入字符串为 <code>"PAYPALISHIRING"</code> 行数为 <code>3</code> 时，排列如下：</p>
//
//<pre>
//P   A   H   N
//A P L S I I G
//Y   I   R</pre>
//
//<p>之后，你的输出需要从左往右逐行读取，产生出一个新的字符串，比如：<code>"PAHNAPLSIIGYIR"</code>。</p>
//
//<p>请你实现这个将字符串进行指定行数变换的函数：</p>
//
//<pre>
//string convert(string s, int numRows);</pre>
//
//<p> </p>
//
//<p><strong>示例 1：</strong></p>
//
//<pre>
//<strong>输入：</strong>s = "PAYPALISHIRING", numRows = 3
//<strong>输出：</strong>"PAHNAPLSIIGYIR"
//</pre>
//<strong>示例 2：</strong>
//
//<pre>
//<strong>输入：</strong>s = "PAYPALISHIRING", numRows = 4
//<strong>输出：</strong>"PINALSIGYAHRPI"
//<strong>解释：</strong>
//P     I    N
//A   L S  I G
//Y A   H R
//P     I
//</pre>
//
//<p><strong>示例 3：</strong></p>
//
//<pre>
//<strong>输入：</strong>s = "A", numRows = 1
//<strong>输出：</strong>"A"
//</pre>
//
//<p> </p>
//
//<p><strong>提示：</strong></p>
//
//<ul>
//	<li><code>1 <= s.length <= 1000</code></li>
//	<li><code>s</code> 由英文字母（小写和大写）、<code>','</code> 和 <code>'.'</code> 组成</li>
//	<li><code>1 <= numRows <= 1000</code></li>
//</ul>
//<div><div>Related Topics</div><div><li>字符串</li></div></div><br><div><li>👍 1642</li><li>👎 0</li></div>
package leetcode.editor.cn;

//Java：Z 字形变换
public class ZigzagConversion_6 {
    public static void main(String[] args) {
        Solution solution = new ZigzagConversion_6().new Solution();
        // TO TEST
        final String in = "PAYPALISHIRING";
        final String out = "PINALSIGYAHRPI";
        int numRows = 4;

        final String outi = solution.convert(in, numRows);
        System.out.println(outi + " " + out.equals(outi));
    }

    //leetcode submit region begin(Prohibit modification and deletion)
    class Solution {
        public String convert(String s, int numRows) {
            if (s == null || s.length() <= numRows || numRows <= 1) {
                return s;
            }

            StringBuilder[] rows = new StringBuilder[numRows];
            for (int i = 0; i < numRows; i++) {
                rows[i] = new StringBuilder();
            }

            boolean flag = true;
            int index = 0;
            for (int i = 0; i < s.length(); i++) {
                final StringBuilder row = rows[index];
                row.append(s.charAt(i));
                if (flag) {
                    if (++index == numRows) {
                        flag = false;
                        index = numRows - 2;
                    }
                    continue;
                }
                if (--index < 0) {
                    flag = true;
                    index = 1;
                }
            }
            final StringBuilder builder = new StringBuilder(s.length());
            for (StringBuilder row : rows) {
                builder.append(row.toString());
            }
            return builder.toString();
        }
    }
//leetcode submit region end(Prohibit modification and deletion)

}